Laminate, lid material, container and packaging bag

Abstract

To provide a laminate which has easy peelability and can stably maintain peeling strength after heat sealing even when it is stored under a high-temperature environment, and a lid material, a container, and a packaging bag which use the laminate.SOLUTION: A laminate includes a sealant film having a seal layer composed of 62 to 72 mass% of a polyester-based resin composition (X) and 28 to 38 mass% of component (C): a polyolefin resin, wherein the polyester-based resin composition (X) is composed of essential component (B): a non-crystalline copolymerized polyester-based resin (B), arbitrary component (A): a polyethylene terephthalate-based resin (A) having a melting point of 190 to 270°C, and arbitrary component (D): a copolymerized polyester-based resin (D) having a melting point of 90 to 180°C, and with respect to the total mass of the polyester-based resin composition (X), the component (A) is 0 to 86 mass%, the component (B) is 5 to 100 mass%, and the component (D) is 0 to 18 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate, a lid material, a container, and a packaging bag. [Background technology]

[0002] In the field of container packaging for food, medicine, etc., containers and packages equipped with easy-to-peel lids that make it easy to open cup- or tray-shaped container bodies are widely used. In particular, for food and medicine containers, polyester resins, polycarbonate resins, etc. are used as materials for the container bodies and lids, and various easy-to-peel lids that make it easy to open these container bodies have been developed and commercialized.

[0003] For example, Patent Document 1 discloses a thermoplastic resin composition containing component (A) as a fusion component: a polyester having a melting peak temperature of 110 to 150°C, component (B) as a cohesive peeling component (easy peeling component): an amine-modified styrene-based thermoplastic elastomer, and component (C) as a moldability auxiliary component: an amorphous polyester and / or polyolefin, and a lid material for an easy-open container, which contains a polyester-based resin having a sealing layer (sealing layer film) formed from this thermoplastic resin composition.

[0004] Patent Document 2 discloses a polyester laminate film comprising a seal layer containing 40 to 70 mass % of a polyethylene terephthalate resin having excellent non-adsorption properties and a crystalline melting peak temperature corresponding to the melting point of 190°C or more and 270°C or less, and 5 to 30 mass % of a thermoplastic polymer polyester resin having a melting point of 90°C or more and 180°C or less, and a support layer containing 90 mass % or more of a polyethylene terephthalate resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-160398 [Patent Document 2] Japanese Patent Publication No. 2023-9803 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Documents 1 and 2 examine the ease of peeling after heat sealing of the film, but do not examine the change in peel strength over time. The polyester laminate film described in Patent Document 2 exhibits sufficient peelability immediately after film formation. However, the inventors of the present invention have found that, depending on the storage environment, a film stored for about a week may have a lower peel strength after heat sealing than a film immediately after film formation. In particular, when the film is stored at high temperatures, sufficient peel strength may not be ensured.

[0007] The main object of the present invention is to provide a laminate that is easily peelable and can stably maintain peel strength after heat sealing even when stored in a high-temperature environment, and a lid material, a container, and a packaging bag that use the laminate. [Means for solving the problem]

[0008] The present invention includes the following aspects. [1] A laminate comprising a sealant film having a seal layer made of a polyester resin composition (X) and a polyolefin resin (hereinafter referred to as "component (C)"), the proportion of the polyester resin composition (X) is 62 to 72 mass% and the proportion of the component (C) is 28 to 38 mass% based on the total mass of the polyester resin composition (X) and the component (C); The polyester resin composition (X) comprises an essential component, a non-crystalline copolymer polyester resin (B) (hereinafter referred to as "component (B)"), an optional component, a polyethylene terephthalate resin (A) (hereinafter referred to as "component (A)") having a melting point of 190°C to 270°C, and an optional component, a copolymer polyester resin (D) (hereinafter referred to as "component (D)") having a melting point of 90°C to 180°C, A laminate, in which the proportion of the component (A) is 0 to 86 mass%, the proportion of the component (B) is 5 to 100 mass%, and the proportion of the component (D) is 0 to 18 mass%, relative to the total mass of the polyester resin composition (X). [2] The laminate according to [1], wherein the proportion of the component (D) relative to the total mass of the polyester resin composition (X) is 1 to 18 mass %. [3] The laminate according to [1] or [2], wherein the component (C) is a linear low-density polyethylene resin. [4] The laminate according to any one of [1] to [3], wherein the component (C) has a melt mass-flow rate at 190°C of 2.0 g / 10 min or less. [5] The laminate according to any one of [1] to [4], wherein the sealant film has a support layer mainly composed of a polyester resin in addition to the sealing layer. [6] A lid material comprising the laminate according to any one of [1] to [5]. [7] A container having a lid material according to [6]. [8] A packaging bag made of the laminate described in any one of [1] to [5]. [Effects of the Invention]

[0009] According to the present invention, there are provided a laminate that is easily peelable and can stably maintain peel strength after heat sealing even when stored in a high-temperature environment, and a lid material, a container, and a packaging bag that use the laminate. DETAILED DESCRIPTION OF THE INVENTION

[0010] <<Laminate>> The laminate of the present invention is a laminate comprising a sealant film having a seal layer made of a polyester resin composition (X) and a component (C). The laminate of the present invention can obtain a peel strength sufficient for easy peeling. The peel strength sufficient for easy peeling can be in the range of, for example, 7 to 18 N / 15 mm.

[0011] [Sealant film] The sealant film used in the present invention may be a film consisting of a sealing layer alone, or may be a film having a support layer containing a polyester resin as a main component in addition to the sealing layer. The sealant film used in the present invention may be a film having another layer in addition to the sealing layer and the support layer, as long as the sealing layer is disposed as the outermost layer.

[0012] (Sealing layer) The seal layer of the sealant film is a layer containing the polyester resin composition (X) and the component (C). The polyester resin composition (X) comprises an essential component (B), an optional component (A), and an optional component (D). The polyester resin composition (X) does not contain any polyester resin other than the components (A), (B), and (D). Component (A): Polyethylene terephthalate resin (A) with a melting point of 190 to 270°C. Component (B): Amorphous copolymer polyester resin (B). Component (D): Copolymer polyester resin (D) with a melting point of 90 to 180°C.

[0013] The mixture forming the sealing layer may further contain other components in addition to the polyester resin composition (X) and the component (C) as long as the effects of the present invention are not impaired.

[0014] <Component (A)> Component (A) is a crystalline polyethylene terephthalate resin having a melting point of 190 to 270°C. Component (A) is preferably a polyethylene terephthalate resin having a melting point of 190 to 270°C, which is a resin obtained by polycondensation of a polycarboxylic acid component and a polyol component, in which 90 mol % or more, preferably 95 mol % or more of the polycarboxylic acid component is a terephthalic acid component, and 90 mol % or more, preferably 95 mol % or more of the polyol component is ethylene glycol. The component (A) may be used alone or in combination of two or more.

[0015] The polycarboxylic acid component may be a derivative such as a free acid, a halide, an alkyl ester in which the alkyl group has 1 to 4 carbon atoms, an alkali metal salt, or an anhydride.

[0016] Examples of polycarboxylic acid components other than terephthalic acid components include aromatic dicarboxylic acids or derivatives thereof, such as phthalic acid, isophthalic acid, dibromoisophthalic acid, hydroxyisophthalic acid, sodium sulfoisophthalate, phenylenedioxydicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylketonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids or derivatives thereof, such as hexahydroterephthalic acid and hexahydroisophthalic acid; aliphatic carboxylic acids or derivatives thereof, such as maleic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, and dodecadicarboxylic acid; and tri- or higher functional carboxylic acids, such as tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, and naphthalenetetracarboxylic acid.

[0017] Examples of polyol components other than the ethylene glycol component include aliphatic diols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, 1,3-butanediol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, polyethylene glycol, and polytetramethylene ether glycol; alicyclic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, and 2,5-norbornanedimethylol; xylitol; aromatic diols such as ethylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, and bis(4-β-hydroxyethoxyphenyl)sulfonic acid; alkylene oxide adducts of aromatic diol components such as an ethylene oxide adduct of 2,2-bis(4'-hydroxyphenyl)propane and a propylene oxide adduct of 2,2-bis(4'-hydroxyphenyl)propane; and tri- or higher functional polyols such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and sugar esters.

[0018] The polymerization components used in the polycondensation of component (A) may contain copolymerization components other than the polycarboxylic acid component and the polyol component. Examples of other copolymerization components include hydroxycarboxylic acids or alkoxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, p-β-hydroxyethoxybenzoic acid, and gallic acid; monoalcohols such as stearyl alcohol, heneicosanol, octacosanol, and benzyl alcohol; and monocarboxylic acids such as stearic acid, behenic acid, benzoic acid, t-butylbenzoic acid, and benzoylbenzoic acid. These other copolymerization components may be used alone or in combination of two or more.

[0019] The melting point of component (A) is 190 to 270°C, preferably 200°C or higher, more preferably 240°C or higher, and preferably 265°C or lower. The melting point is the temperature of the endothermic peak with the greatest intensity detected during the second heating step, which is performed at a heating rate of 10°C / min, when a differential scanning calorimeter (DSC) measurement is performed in accordance with JIS K 7121. For commercially available products, the melting point listed in the catalog may be used.

[0020] The intrinsic viscosity of component (A) is not particularly limited. For example, it is 0.50 dL / g or more, preferably 0.60 dL / g or more, more preferably 0.70 dL / g or more, and for example, 0.95 dL / g or less, preferably 0.92 dL / g or less, more preferably 0.90 dL / g or less. If the intrinsic viscosity is equal to or greater than the lower limit, it is easy to suppress a decrease in melt viscosity during the film formation process, and it is easy to form tubular bubbles with a stable diameter, for example, during inflation film formation. If the intrinsic viscosity is equal to or less than the upper limit, it is possible to prevent the melt viscosity of the mixture from becoming too high. Therefore, for example, when film formation is performed using a multilayer cast film forming machine equipped with a feed block, the mixture is likely to spread to the ends of the die width direction. The intrinsic viscosity was measured by dissolving component (A) at an arbitrary concentration in a mixed solvent of phenol and tetrachloroethane in a volume ratio of 1:1, and measuring the viscosity at 25°C using an Ubbelohde viscometer.

[0021] Commercially available products of component (A) include, for example, the "NEH series" manufactured by Unitika and the "S103" manufactured by Rikko.

[0022] <Ingredient (B)> Component (B) is a non-crystalline copolymer polyester resin. Component (B) imparts sealing properties to the seal layer and enhances the dispersibility of component (C) in polyester resin composition (X), and also suppresses a decrease in peel strength when heat-sealing is performed after a certain period of time has elapsed since the film was formed.

[0023] Component (B) can be obtained by polycondensation of a polycarboxylic acid component and a polyol component selected so as not to have a melting point. Commercially available copolymer polyester resins that are classified as "amorphous" by resin manufacturers can be used. The component (B) may be used alone or in combination of two or more.

[0024] The polycarboxylic acid component used in the polycondensation of component (B) is selected, for example, from the polycarboxylic acid components exemplified for component (A) so as to give a polyester resin having no melting point. The polyol component used in the polycondensation of component (B) is selected, for example, from the polyol components exemplified for component (A) so as to give a polyester resin having no melting point.

[0025] Commercially available products of component (B) include, for example, the "Vylon (registered trademark) series" manufactured by Toyobo.

[0026] <Ingredient (D)> Component (D) is a crystalline copolymer polyester resin having a melting point of 90 to 180° C. Component (D) has the function of increasing the dispersibility of component (C) in polyester resin composition (X) in order to obtain film formability, good film appearance, and peel strength that exhibits good peelability. Component (D) is obtained by polycondensing a polycarboxylic acid component and a polyol component selected so as to have a melting point of 90 to 180°C. The component (D) may be used alone or in combination of two or more.

[0027] The polycarboxylic acid component used in the polycondensation of component (D) is selected, for example, from the polycarboxylic acid components exemplified for component (A) so as to have a melting point of 90 to 180° C. Terephthalic acid is preferred as the polycarboxylic acid component used in the polycondensation of component (D). The polyol component used in the polycondensation of component (D) is selected from the polyol components exemplified for component (A) so as to have a melting point of 90 to 180° C. It is preferred that part of the ethylene glycol in the polyol component used in the polycondensation of component (D) is cyclohexanedimethanol.

[0028] The melting point of component (D) is 90 to 180°C, preferably 95°C or higher, more preferably 100°C or higher, and preferably 150°C or lower, more preferably 135°C or lower. The melting point of component (D) is a value measured by the method described for component (A).

[0029] Commercially available products of component (D) include, for example, the Vylon (registered trademark) series manufactured by Toyobo Co., Ltd. and the PETG (registered trademark) series manufactured by Eastman Chemical Company.

[0030] <Ingredient (C)> Component (C) is a polyolefin resin. The component (C) has the function of impairing heat sealability by dispersing in the polyester resin composition (X) in order to impart easy peelability to the seal layer.

[0031] As component (C), a resin obtained by polymerizing one or more α-olefins having 2 to 20 carbon atoms is preferred. Examples of component (C) include low-density polyethylene resins, linear low-density polyethylene resins, medium-density polyethylene resins, high-density polyethylene resins, polypropylene resins, and copolymers of ethylene and an α-olefin having 3 to 20 carbon atoms. Component (C) is more preferably a polyethylene resin, and from the viewpoint of low-temperature sealing properties, an ethylene-α-olefin copolymer, which is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms and is also called a linear low-density polyethylene resin, is even more preferred. The component (C) may be used alone or in combination of two or more.

[0032] Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecene. Of these, the α-olefin having 3 to 20 carbon atoms is preferably at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0033] The catalyst used in producing a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is not particularly limited, and examples thereof include Ziegler-Natta catalysts and metallocene catalysts. Metallocene catalysts are preferred as they can easily produce linear low-density polyethylene with a narrow molecular weight distribution and have excellent impact resistance.

[0034] The density of component (C) is not particularly limited, and may be, for example, 0.900 g / cm 3 or more, preferably 0.913 g / cm 3 or more, and for example, 0.968 g / cm 3 or less, preferably 0.920 g / cm 3 or less, more preferably 0.917 g / cm 3 When the density of component (C) is equal to or greater than the lower limit, blocking of the sealant film or a laminate using the same is easily suppressed. When the density of component (C) is equal to or less than the upper limit, the transparency of the seal layer is good, making it easy to visually recognize the contents of the package, and the flexibility of the sealant film is improved, making it less likely to feel heavy when peeled off.

[0035] The density of low-density polyethylene resin is 0.900 g / cm 3 More than 0.930g / cm 3 The density of medium density polyethylene resin is preferably less than 0.930 g / cm 3 More than 0.942g / cm 3 The density of high density polyethylene resin is preferably less than 0.942 g / cm 3 More than 0.968g / cm 3 The following is preferred: The density of polypropylene resin is 0.90 g / cm 3 More than 0.91g / cm 3 Less than is preferred. The density is a value measured in accordance with the density gradient tube method in JIS K 7112. In the case of commercially available products, the density value listed in the catalog may be used.

[0036] The melt mass flow rate (MFR) of component (C) at 190°C is preferably 2.0 g / 10 min or less. If the MFR of component (C) is 2.0 g / 10 min or less, peel strength that allows easy peeling is easily obtained, and further, a good peel surface appearance in which the peel interface appears white without the occurrence of stringiness or the like is easily obtained. Furthermore, even when component (C) is a linear low-density polyethylene-based resin, if the MFR is higher than 2.0 g / 10 min, low-temperature sealability tends to be poor. Therefore, when low-temperature sealability is required, it is preferable to use a linear low-density polyethylene-based resin with an MFR of 2.0 g / 10 min or less as component (C). The MFR is a value measured in accordance with JIS K 7210-1 "Method for determining melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics." The MFR of the polyolefin resin in the present invention is a value measured at a cylinder temperature of 190°C and a weight of 2.16 kg, regardless of the type of polyolefin resin.

[0037] Commercially available polyethylene resins of component (C) include, for example, "Novatec" manufactured by Nippon Polyethylene and "Evolue (registered trademark)" manufactured by Prime Polymer. Commercially available polypropylene resins include, for example, "Prime Polypro (registered trademark)" manufactured by Prime Polymer.

[0038] <Other ingredients> Examples of other components include various additives such as antistatic agents, antioxidants, lubricants, antiblocking agents, antifogging agents, colorants, ultraviolet absorbers, dispersants, and fillers. Examples of the anti-blocking agent include inorganic particles such as silica, zeolite, and talc, and organic resin particles such as silicone resin and (meth)acrylic resin. Examples of colorants include organic pigments and inorganic pigments. Examples of fillers include talc and calcium carbonate.

[0039] The sealing layer may contain other resins other than the polyester resin composition (X) and component (C) as other components. Examples of other resins include polyester resins other than components (A), (B), and (D), and specific examples include polybutylene terephthalate resins. The other components may be used alone or in combination of two or more.

[0040] <Composition> The proportion of the polyester resin composition (X) in the seal layer is 62% by mass or more, preferably 65% ​​by mass or more, based on the total mass of the polyester resin composition (X) and component (C). The proportion of the polyester resin composition (X) is 72% by mass or less, preferably 70% by mass or less. The proportion of the polyester resin composition (X) in the seal layer based on the total mass of the polyester resin composition (X) and component (C) is determined by the proportion of component (C) described below.

[0041] The proportion of component (A) in polyester resin composition (X) is 0% by mass or more, preferably 25% by mass or more and 86% by mass or less, based on the total mass of polyester resin composition (X). The higher the proportion of component (A), the more easily peelable the film can be obtained after film formation, and even if heat-sealing is performed after a certain period of time, the more effectively the film can be prevented from decreasing in peel strength over time. When component (A) is within the above range, a sealant film can be obtained that has peel strength suitable for easy peeling and excellent appearance of the peeled surface.

[0042] The proportion of component (B) in the polyester-based resin composition (X) is 5% by mass or more, preferably 13% by mass or more, and 100% by mass or less, preferably 65% ​​by mass or less, based on the total mass of the polyester-based resin composition (X). When the proportion of component (B) is equal to or greater than the lower limit, even when heat-sealing is performed after a certain period of time, a decrease in peel strength can be suppressed, thereby suppressing deterioration of the easy-peel function. This is thought to be because component (B) can suppress the crystallization of component (A) together with component (D) over time. Furthermore, even when the proportion of component (B) in the polyester-based resin composition (X) is 100% by mass, a decrease in peel strength when heat-sealing is performed after a certain period of time can be suppressed, and a stable easy-peel peel strength can be maintained. However, a lower proportion of component (B) in the polyester-based resin composition (X) increases the yield of components derived from terephthalic acid and ethylene glycol during chemical recycling of the sealant film, resulting in excellent recyclability.

[0043] The combined mass ratio of components (A) and (B) in the polyester-based resin composition (X) is preferably 82% by mass or more, more preferably 87% by mass or more, and 100% by mass or less, preferably 98% by mass or less, based on the total mass of the polyester-based resin composition (X). Even when the content of component (B) in the polyester-based resin composition (X) is 100% by mass and the content of component (A) is 0% by mass, a decrease in peel strength when heat-sealed after a certain period of time can be suppressed, and a stable peel strength that allows easy peeling can be maintained. Reducing the proportion of component (B) and increasing the proportion of component (A) in the polyester-based resin composition (X) increases the yield of components derived from terephthalic acid and ethylene glycol when the sealant film is chemically recycled, resulting in excellent recyclability.

[0044] The proportion of component (D) in the polyester resin composition (X) is 0% by mass or more, preferably 1% by mass or more, more preferably 6% by mass or more, and 18% by mass or less, preferably 13% by mass or less, based on the total mass of the polyester resin composition (X). When the proportion of component (D) is 0% by mass, the seal layer has easy peelability and a good peel surface appearance. However, the peel strength is high at about 17 N / mm. To obtain a lower peel strength with even better easy peelability, it is preferable to add 1% by mass or more of component (D) to the polyester resin composition (X). Furthermore, when the proportion of component (D) is 1% by mass or more, the sealant film has excellent film formability and a good film appearance. When the proportion of component (D) exceeds 18% by mass, good easy peelability is obtained immediately after film formation, but when heat-sealed after a certain period of time, the peel strength decreases compared to after film formation, and the easy peel function is lost. If the proportion of the component (D) is 18% by mass or less, the peel strength will not change much even when heat-sealed after a certain period of time, and a stable peel strength that allows easy peeling can be maintained. If the proportion of the component (D) is 13% by mass or less, even when heat-sealed after a certain period of time during high-temperature storage, a decrease in peel strength will be suppressed, and a stable peel strength that allows easy peeling can be maintained.

[0045] The proportion of component (C) in the seal layer is 28% by mass or more, preferably 30% by mass or more, based on the total mass of the polyester resin composition (X) and component (C). When the proportion of component (C) is equal to or greater than the lower limit, excellent peel strength can be obtained. When the proportion of component (C) is less than the lower limit, the dispersion amount is insufficient to exhibit easy peelability with respect to the polyester resin composition (X), and the peel strength tends to be high. Furthermore, the proportion of component (C) is 38% by mass or less, preferably 35% by mass or less. When the proportion of component (C) is equal to or less than the upper limit, the loss of heat sealability due to an excess of component (C) can be prevented, and excellent peel strength can be obtained. Furthermore, when a support layer is provided, excellent interlayer strength between the seal layer and the support layer is also achieved. When the proportion of component (C) exceeds the upper limit, heat sealability is impaired, making heat sealing impossible. Even if heat sealing is possible, the peel strength is extremely low and stringiness and other poor peel surface appearance tend to occur.

[0046] The proportion of the other resin in the sealing layer is preferably 3 parts by mass or less per 100 parts by mass of the total mass of the polyester resin composition (X) and the component (C).

[0047] (support layer) The sealant film used in the present invention may have a support layer in addition to the sealing layer. The support layer is a layer having a surface to be bonded to another film, etc., when a laminate is produced using the sealant film. When the sealant film is produced by a co-extrusion method, the provision of the support layer allows the sealant film to be produced more stably.

[0048] The support layer is a layer containing a polyester resin as a main component. The polyester resin used in the support layer is mainly a polyethylene terephthalate resin, and other examples include a polybutylene terephthalate resin. Examples of the polyethylene terephthalate resin used in the support layer include the same polyethylene terephthalate resin as component (A). The polyethylene terephthalate resin contained in the support layer and the polyethylene terephthalate resin contained in the seal layer may be the same or different, but from the viewpoints of reducing production costs and recycling, it is preferable that the polyethylene terephthalate resins contained in the support layer and the seal layer are the same.

[0049] The support layer may contain components other than the polyethylene terephthalate-based resin. Examples of other components that can be contained in the support layer include resins other than the polyethylene terephthalate-based resin and additives.

[0050] Examples of resins other than polyethylene terephthalate resins include copolymer polyester resins, which are other polyester resins, polybutylene terephthalate resins, and polyolefin resins. Examples of the additives include the same additives as those exemplified for the sealing layer. The other components contained in the support layer may be used alone or in combination of two or more.

[0051] The content of other components in the support layer is preferably less than 15 parts by mass relative to 100 parts by mass of the polyethylene terephthalate resin.

[0052] (Other layers) The sealant film may have layers other than the sealing layer and the support layer, as long as the sealing layer is located on the surface of the sealant film.

[0053] (Sealant film thickness) The thickness of the sealant film is not particularly limited, and is, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and is, for example, 200 μm or less, preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less. When the thickness of the sealant film is within the above range, it is easy to obtain a film that has a good balance between flexibility and rigidity. Furthermore, when the thickness of the sealant film is within the above range, it is easy to obtain peel strength that provides practical easy peelability, and it is easy to peel a lid material using the laminate of the present invention containing the sealant film from a package, and it is easy to ensure excellent easy peelability that allows a packaging bag using the laminate of the present invention containing the sealant film to be easily opened.

[0054] The ratio of the thickness of the seal layer to the total thickness of the sealant film is not particularly limited, and is, for example, 5% or more, preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more, and is, for example, 40% or less, preferably 30% or less. A smaller thickness ratio of the seal layer is advantageous in terms of cost. Furthermore, a smaller thickness ratio of the seal layer and a larger thickness ratio of the support layer allows for stable film formation of the sealant film, and subsequent handling properties such as winding are also favorable. When the thickness ratio of the seal layer is equal to or greater than the lower limit, for example, the sealant film is easily extruded uniformly during film formation. As a result, when the sealant film is heat-sealed to a container body or the like, portions where the support layer is directly welded to the container body or the like are unlikely to occur. Furthermore, when sealant films are heat-sealed together, portions where the support layers are directly welded to each other are unlikely to occur. This makes it easier to prevent excessive welding strength and a decrease in ease of peeling.

[0055] The ratio of the thickness of the support layer to the total thickness of the sealant film is not particularly limited and is, for example, 60% or more, preferably 70% or more, and for example, 95% or less, preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less. If the ratio of the thickness of the support layer is equal to or greater than the lower limit, the sealant film can be easily formed stably, and subsequent handling such as winding is also improved.

[0056] (Ratio of polyester resin in sealant film) In the seal layer, components (A), (B), and (D) are polyester resins. That is, of the polyester resin composition (X) and component (C) constituting the seal layer, 62 to 72 mass% of the polyester resin composition (X) is used, excluding 28 to 38 mass% of component (C). In addition, even when the sealant film used in the present invention has a support layer, the support layer is mainly composed of a polyethylene terephthalate resin. By adjusting the proportion of polyethylene terephthalate resin in the support layer and the thickness of the support layer in the sealant film, the sealant film can be made into a film with 90% or more by mass of polyester resin. This allows it to be a packaging material whose main component is a single material with high recyclability, known as a "monomaterial," in accordance with the United Nations' Sustainable Development Goals (SDGs).

[0057] (Method of manufacturing sealant film) The method for producing the sealant film used in the present invention is not particularly limited. For example, in the case of a sealant film having a seal layer and a support layer, a coextrusion method can be used in which the resin components constituting the seal layer and the support layer are fed into a multilayer T-die molding machine or a multilayer inflation molding machine and coextruded. The coextrusion method using a multilayer T-die molding machine or a multilayer inflation molding machine is preferred because it requires fewer steps, is simple, and can achieve sufficiently high adhesive strength between layers. Other methods that may be used include melt extrusion lamination, in which the resin components constituting the sealing layer are melt extrusion laminated onto at least one surface of the support layer, and dry lamination, in which the sealing layer and the support layer are formed separately and then dry laminated.

[0058] [Laminated structure] The laminate of the present invention may be, for example, a laminate in which a sealant film is used as a sealant film layer and a substrate layer is provided on the surface of the support layer of the sealant film opposite to the sealing layer.

[0059] (base material layer) The base layer is a layer with high strength and does not deform even at a temperature at which the sealant film partially melts when the laminate is heat-sealed. Examples of the substrate layer include unstretched films, uniaxially stretched films, or biaxially stretched films of polyester resins, polyamide resins, polyolefin resins, etc.; gas barrier films obtained by depositing aluminum, silica, alumina, etc. on these films; paper; and metals such as aluminum foil. From the viewpoint of mono-materialization, a polyester resin film is preferred as the substrate layer. The laminate may have only one base layer, or may have two or more base layers that are the same as or different from each other. The base layer may be subjected to processing such as coloring and printing. By using these substrate layers, it is possible to obtain a laminate that is excellent in design, gas barrier properties, light blocking properties, pinhole resistance, curl resistance, and the like.

[0060] In the laminate, an intermediate layer may be provided between the sealant film layer made of a sealant film and the substrate layer, or between a plurality of substrate layers. Examples of intermediate layers include a printing layer, an adhesive layer, a primer layer, and a vapor-deposited layer. When the laminate of the present invention has an intermediate layer, the intermediate layer may be of only one type or of two or more types.

[0061] (Method of manufacturing laminate) Examples of methods for producing the laminate of the present invention include a method of laminating a substrate layer on a sealant film by dry lamination, a method of laminating a substrate layer on a sealant film by sandwich lamination using molten polyethylene or the like, a method of laminating a sealant film on a substrate layer by multilayer extrusion lamination, and a method of co-extruding all layers constituting the laminate. Dry lamination is preferred because it allows the substrate layer, etc. to be laminated via a thin adhesive and can increase the mono-material ratio.

[0062] 《Lid materials, containers, packaging bags》 The lid material of the present invention is composed of the laminate of the present invention. The container of the present invention includes the lid of the present invention. Examples of the container of the present invention include a container that includes the lid of the present invention and a container body, the container body having a welding part such as a flange that can be tightly attached to the lid, and a storage part that stores contents such as food.

[0063] The shape of the container body is not particularly limited, and any shape such as a cup shape or a tray shape can be adopted. The position of the welded portion provided on the container is not particularly limited, and it can be provided, for example, on the top surface of the container body.

[0064] After the contents are placed in the storage section, the lid material and the container body can be welded together by heat-sealing the sealing layer of the lid material and the welded part of the container body while they are in contact. It is preferable to provide a gripping part called a "tab" that is not heat-sealed by making a part of the lid material protrude from the welded part of the container body or by providing an unsealed part as a peel-start part when opening.

[0065] The packaging bag of the present invention is formed from the laminate of the present invention. The shape of the packaging bag is not particularly limited, and examples thereof include palm-shaped bags, flat bags, side gusset bags, bottom gusset bags, and square-bottom packaging bags. The packaging bag may be provided with a mouth such as a spout or a zipper.

[0066] The laminate of the present invention described above, and the lid material, container, and packaging bag using the same can maintain excellent peelability even when using a sealant film that has been in use for some time since film formation, and the appearance of the peeled surface is also good. [Example]

[0067] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following descriptions.

[0068] [Sealing layer raw materials] Ingredient (A) A-1: Polyethylene terephthalate resin, Li-Peng "S103", intrinsic viscosity: 0.810 dl / g, melting point: 246°C. ·Component (B) B-1: Amorphous copolymer polyester resin, "Vylon (registered trademark) SI173" manufactured by Toyobo Co., Ltd., catalog softening point: 185°C. ·Component (C) C-1: Linear low-density polyethylene resin, "Novatec LL (registered trademark) UF420" manufactured by Japan Polyethylene Corporation, density: 0.924 g / cm 3 , MFR at 190°C: 0.9g / 10min. C-2: Block polypropylene resin, Prime Polypro (registered trademark) F703 manufactured by Prime Polymer Co., Ltd., density: 0.9 g / cm 3 , MFR at 190°C = 1.3 g / 10 min. C-3: Linear low-density polyethylene resin, "Evolue® SP1540" manufactured by Prime Polymer Co., Ltd., density: 0.913 g / cm 3 , MFR at 190°C: 3.8g / 10min. ·Component (D) D-1: Copolymer polyester resin, "Vylon (registered trademark) GM913" (manufactured by Toyobo Co., Ltd., catalog melting point: 126°C).

[0069] [Support layer materials] ·Component (E) E-1: Polyethylene terephthalate resin, "S103" (manufactured by Li-Peng, intrinsic viscosity: 0.810 dl / g, melting point: 246°C).

[0070] [glue] F-1: Urethane adhesive, "RU-40" manufactured by Rock Paint. [Film for base layer] H-1: Biaxially oriented polyethylene terephthalate film, "E5102" manufactured by Toyobo Co., Ltd., thickness 12 μm.

[0071] [Examples 1 to 16 and Comparative Examples 1 to 5] The components for forming the seal layer and the components for forming the support layer were prepared by mixing the components in a Henschel mixer according to the composition shown in Table 1. These components for forming the seal layer and the components for forming the support layer were placed in the hopper of a two-layer T-die molding machine and formed into a film at a die temperature of 285°C, yielding a two-layer sealant film having a seal layer and a support layer with the thicknesses shown in Table 1.

[0072] After corona treatment was performed on the surface of the support layer of the sealant film, adhesive F-1 was applied to the surface at an average solid content of 3.3 g / m 2 By the dry lamination method used in the above, film H-1 was laminated as a substrate layer on the support layer side of the sealant film, and aging was carried out at 40° C. for 3 days to obtain a laminate.

[0073] [Table 1]

[0074] <Evaluation of peel strength> [Peel strength (1)] The laminate obtained in each example was heat-sealed at 120°C over a 20 mm width at the overlapping seal layer, and both ends of the heat-sealed portion were cut off to obtain a 15 mm wide test piece for measuring peel strength. This test piece was left standing for 24 hours at 23°C and 50% relative humidity. Then, in accordance with JIS Z 0238, a T-peel test was performed at a peel rate of 300 mm / min using a tensile tester, and the peel strength per 15 mm width was measured. The measured peel strength was evaluated according to the following criteria. (Evaluation criteria) 1: Not heat sealable. 2: Heat sealable, but peel strength is less than 7N / 15mm. 3: Heat sealable, peel strength is 7 to 18 N / 15 mm, and easy peelability is good. 4: Heat sealable, but peel strength exceeds 18N / 15mm, making it difficult to peel. 5: Heat sealable but not peelable, breaks at seal edge.

[0075] [Peel strength (2)] The laminate obtained in each example was heat-sealed at 160°C over a 20 mm width at the overlapping seal layer, and both ends of the heat-sealed portion were cut off to obtain a 15 mm wide test piece for measuring peel strength. This test piece was left standing for 24 hours at 23°C and 50% relative humidity. Then, in accordance with JIS Z 0238, a T-peel test was performed at a peel rate of 300 mm / min using a tensile tester, and the peel strength per 15 mm width was measured. The measured peel strength was evaluated using the same criteria as for peel strength (1).

[0076] [Peel strength (3)] The laminate obtained in each example was aged in an oven at 40°C for 30 days, and then the peel strength per 15 mm width was measured in the same manner as in Peel Strength (2). The measured peel strength was evaluated according to the same criteria as in Peel Strength (1).

[0077] [Peel strength 4] The laminate obtained in each example was aged in an oven at 50°C for 30 days, and then the peel strength per 15 mm width was measured in the same manner as in Peel Strength (2). The measured peel strength was evaluated according to the same criteria as in Peel Strength (1).

[0078] <Appearance of peeled surface> The peeled surface of the test piece for measuring peel strength after measuring peel strength (1) was visually observed and evaluated according to the following criteria. (Evaluation criteria) A: The peeled surface is uniformly whitened, and there is no stringiness or residual film. B: The peeled surface is uniformly whitened, but some stringiness occurs. C: Sealing is not possible, so the peeled surface cannot be observed. D: Peeling is not possible, so the peeled surface cannot be observed.

[0079] Table 2 shows the evaluation results of Examples 1 to 16 and Comparative Examples 1 to 5.

[0080] [Table 2]

[0081] As shown in Table 2, the laminates of Examples 1 to 11 and 13 to 15, in which the seal layer contained polyester resin composition (X) and component (C) in the ratio specified by the present invention, exhibited peel strength sufficient for easy peeling when heat-sealed at 160°C, and were able to maintain such peel strength even after 30 days of storage at 40°C. Furthermore, the laminate of Example 12, in which the seal layer contained components (A) to (C) in the ratio specified by the present invention and the polyester resin composition (X) did not contain component (D), exhibited peel strength sufficient for easy peeling when heat-sealed at 160°C, and was able to maintain such peel strength even after 30 days of storage at 40°C.

[0082] A comparison of Examples 1 and 2 to 5, which contain the same types and proportions of components (C) and (D), reveals that increasing the proportion of component (B) significantly suppresses the decrease in peel strength after heat sealing, even after storage at 50°C for one month, and maintains a peel strength that allows easy peeling. A comparison of Examples 13 to 15, which contain the same types and proportions of components (C) and (D), reveals that a low proportion of component (A) and a high proportion of component (B) significantly suppresses the decrease in peel strength after heat sealing, even after storage at 50°C for one month, and maintains a peel strength that allows easy peeling. Furthermore, a comparison of Examples 13 to 15 and 16, which contain the same type and proportion of component (C), reveals that Example 16, in which the polyester resin composition (X) contains only component (B) and does not contain components (A) and (D), also significantly suppresses the decrease in peel strength after heat sealing, even after storage at 50°C for one month, and maintains a peel strength that allows easy peeling. However, in Examples 13 to 16, the proportion of component (B), which is a copolymer polyester resin, in the polyester resin composition (X) is high, and the yield of components derived from terephthalic acid and ethylene glycol is low when the laminate is chemically recycled, so that the recyclability is inferior to that of the other Examples.

[0083] A comparison of Example 3 and Example 9, which have similar types and proportions of component (A) and component (C), shows that a lower proportion of component (D) is more effective in suppressing a decrease in peel strength after heat sealing, even after 30 days of storage at 50°C, and is able to maintain easy peelability. A comparison of Examples 4, 10, and 11, which differ only in the type of component (C), reveals that by using a linear low-density polyethylene resin with an MFR of 2.0 g / 10 min or less at 190°C, sufficient peel strength is easily obtained even with heat sealing at 120°C, and the low-temperature heat sealability is excellent, and it is easy to achieve both maintaining peel strength that allows easy peeling and a good peel surface appearance. Furthermore, although not shown in Table 2, the laminates of Examples 1 to 11 and 13 to 15, which contained 1.0 mass % or more of component (D) in the polyester resin composition (X), had excellent film formability and good film appearance compared to the laminates of Examples 12 and 16, which did not contain component (D).

[0084] On the other hand, the laminate of Comparative Example 1, in which the sealing layer contained only the component (A) and did not contain the components (B) to (D), was strongly heat-sealed and did not exhibit easy peelability. In the laminate of Comparative Example 2, in which the sealing layer did not contain component (B), a peel strength was obtained that allowed easy peeling when heat-sealed at both 120°C and 160°C. However, after 30 days of storage at both 40°C and 50°C, the peel strength after heat-sealing decreased and the heat-sealability was lost. The laminate of Comparative Example 3, in which the proportion of component (C) contained in the sealing layer was less than 28% by mass, exhibited high peel strength when heat-sealed at both 120°C and 160°C, and did not exhibit easy peelability. The laminate of Comparative Example 4, in which the proportion of component (C) contained in the seal layer exceeded 38% by mass, could not be heat-sealed. The laminate of Comparative Example 5, in which the proportion of component (D) in the polyester resin composition (X) contained in the seal layer exceeded 18% by mass, was heat-sealable immediately after film formation, but was unable to be heat-sealed after 30 days of storage at either 40°C or 50°C.

Claims

1. A laminate comprising a sealant film having a seal layer made of a polyester resin composition (X) and a polyolefin resin (hereinafter referred to as "component (C)"), a proportion of the polyester resin composition (X) is 62 to 72 mass% and a proportion of the component (C) is 28 to 38 mass% relative to the total mass of the polyester resin composition (X) and the component (C); The polyester resin composition (X) comprises an essential component, a non-crystalline copolymer polyester resin (B) (hereinafter referred to as "component (B)"), an optional component, a polyethylene terephthalate resin (A) (hereinafter referred to as "component (A)") having a melting point of 190°C to 270°C, and an optional component, a copolymer polyester resin (D) (hereinafter referred to as "component (D)") having a melting point of 90°C to 180°C, A laminate, wherein the proportion of the component (A) is 0 to 86% by mass, the proportion of the component (B) is 5 to 100% by mass, and the proportion of the component (D) is 0 to 18% by mass, relative to the total mass of the polyester-based resin composition (X).

2. 2. The laminate according to claim 1, wherein the proportion of the component (D) relative to the total mass of the polyester resin composition (X) is 1 to 18 mass %.

3. The laminate according to claim 1, wherein the component (C) is a linear low-density polyethylene resin.

4. 2. The laminate according to claim 1, wherein the component (C) has a melt mass-flow rate at 190°C of 2.0 g / 10 min or less.

5. The laminate according to claim 1 , wherein the sealant film has a support layer containing a polyester resin as a main component in addition to the sealing layer.

6. A lid material comprising the laminate according to any one of claims 1 to 5.

7. A container comprising the lid material according to claim 6.

8. A packaging bag comprising the laminate according to any one of claims 1 to 5.

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